FC11 emits moonlight even when off

A few years ago, I bought a Wurkkos FC11 (not the FC11C) based on some recommendations by this community. If I recall correctly, it’s an LH351D emitter in 4000K.

It continues to be a great light for me, so much so that my girlfriend kept asking to borrow it, then asked for one of her own, and soon after received her very own FC11.

Over the past year, my FC11 gradually started to emit even when switched off, almost imperceptibly at first but now at nearly the same brightness as moonlight mode.
Photos are a comparison of switched off and moonlight mode.

What is causing the emitter to be powered even when switched off?

Is this a sign of a future failure?

If it matters, my girlfriend’s FC11 does not exhibit this issue but hers is also 1-2 years newer than mine.

Thanks in advance!